Got to meet another new puppy in our neighborhood, as some folks moved in down
the block with a little Rhodesian Ridgeback, who seems all the smaller in
contrast to the enormous 90 lb Rhodey owned by The Devicers. Puppies are always
cute, but this one is especially so, though our neighbor's teensy Chihuahua mix
didn't think so, as she tried to pick a fight with him. I tried to explain to
her that a 5 lb dog is not probably a good match for a lion hunter, but she
didn't seem convinced.

Here's a question for the experts of larger dogs. If you've got a larger animal, say a Great Dane, do they tend to live shorter lives due to their size/weight

I would guess on average that larger dogs do live shorter lives, but it probably has nothing to do with the size/breed. Sure some larger dog breeds might naturally have short life expectancies but I would guess over all it comes down to exercise.

A 1 mile walk for a small dog is good exercise, where as a large dog with much longer legs a 1 mile walk would be just a warm up. I know lots of dog owners, and I doubt 99% of large dogs in America get even 1/4th the amount of exercise they really need.

Just my guess though. And since these dogs do not get enough exercise it would be near impossible to tell from just nation wide statistics alone also. The quality of your life (or dogs) affects the longevity of your life.